Authorities spurred a media storm by revisiting actress Natalie Wood's death, but their purpose is unclear.

When Natalie Wood died in the cold, dark water near Santa Catalina Island 30 years ago, the story elicited a frenzy of media attention. Rumors of suicide or foul play never disappeared, even after authorities closed the case as the accidental drowning of a 43-year-old actress who'd been drinking and couldn't swim.

It is unclear what compelling evidence — if any — prompted the Los Angeles County Sheriff's Department to reopen the case, and what accounts for the peculiar timing. Detectives formally announced the probe Friday, two weeks from the three-decade anniversary of Wood's death, and days before the scheduled retrospective on the case on CBS' "48 Hours."

What is new, apparently, are the ominous yet ambiguous pronouncements of Dennis Davern, captain of the yacht on which Wood was last seen alive with husband Robert Wagner and her "Brainstorm" co-star Christopher Walken.

Davern, who co-wrote a book about the case, made the TV news rounds Friday, claiming Wagner was responsible for Wood's death but refusing pointed requests to give details. He was joined by other figures in the case including Wood's sister, Lana, who has long campaigned for a new investigation.

Their remarks reverberated in a media echo chamber that makes the tabloid pace of 1981 seem stately by comparison. Amid all the recent noise came the question: What were detectives doing?

Bill McSweeney, chief of the Sheriff's Department Detective Division , said he hoped the new probe would resolve unanswered questions and "put an end to the phone calls from the media and others."

At least on Friday, the opposite seemed to be happening.

More than 40 journalists crammed around a podium outside department headquarters Friday morning for the news conference as the 30th anniversary of Wood's death suddenly received the stamp of actual news.

Kotaro Kato, a reporter for Japan's Nippon TV, said he was covering the event not because of Wood's celebrity but because other media outlets were covering the event. "In Japan, Natalie Wood is not so popular," Kato said. "But I think people may be interested because the story is catching such fire in the U.S."

Some reporters stood, some knelt. They tapped on smart phones and laptops as the minutes passed. Behind them stood rows of TV news trucks, satellite dishes extending toward the sky. At about 10:53 Steve Whitmore, a sheriff's spokesman, emerged to make an announcement. "In about three minutes, we're going to go live," he said.

Then came homicide Lt. John Corina, to say little that everyone didn't already know.

"Recently we received information which we felt was substantial enough to make us take another look at this case," Corina said. He said "several sources" had come forward, but he refused to say what the new information might be. Nor would he say who detectives had interviewed so far, or who they planned to interview.

Was Robert Wagner a suspect? "No," Corina replied firmly.

Has murder been ruled out? "If our investigation, at the end of it, points to something else then we'll address that. But right now her death is an accidental drowning."

Corina said that the department was "not concerned" with the anniversary date of Wood's death, and that recent media coverage — including Davern's book — was "inconsequential."

The press seemed largely disappointed by the lack of new information. "This is very frustrating," one TV news reporter said at the news conference.

Inside the Sheriff's Department, where veteran investigators know that three-decade-old cases are forbiddingly hard even when they involved non-celebrity players, some officials were trying to privately reduce expectation. "Whatever happens, it is unlikely to change the outcome of the original investigation so many decades after the death," said a source familiar with the investigation.

Another source said officials hope that media reports don't "build up expectations because the reality is [that] anything like this is tough." Both sources spoke on the condition of anonymity because the case was ongoing.

Suzanne Ely, a professor of journalism at New School University, said she was skeptical that the media spectacle would lead to anything new in the investigation. "There's nothing new here," said Ely, who has taught courses on celebrity and tabloid journalism. "It appears that law enforcement is following media, not the other way around."

Frank Griffin, a celebrity photographer, said the development in the Wood case seemed to arrive at a slow point for celebrity news — and that perhaps that's the point.

The motives behind the "new information" in the Wood case remain a mystery. Wagner pointed that out in a statement his publicist released Thursday night, saying he supported the sheriff's inquiry but was concerned about "those simply trying to profit from the 30-year anniversary of her tragic death."